Metering jet adjustable fuel by-pass



Nov. 5, 1968 D. A. RElSE 3,409,277

METERING JET ADJUSTABLE FUEL BY-PASS Filed June 24, 1966 2 Sheets-Sheet1 49 27 1% fifl ,72 /6 wk fi ,0 f A 66 I v -57 M F c. l.

-67 j? 2/ 4? v 66 j i /5 56 57 62 2 5a 55 .2. I. 53 F IISVENTOR 56DONALD A. REISE 55 F l 0.3. fl

ATTORNEY Nov. 5, 1968 D. A. REISE 3,409,277

METERING JET ADJUSTABLE FUEL BY-PASS Filed June 24, 1966 2 Sheets-Sheet2 FIGS.

X W /03 g /0/ INVENTOR FIG. 5. DONALD A. REISE ATTORNEY ABSTRACT OF THEDISCLOSURE "A carburetor having a main fuel metering jet and a main fuelmetering rod is further provided with an auxili'ary adjustable main fuelsupply port which port is rendered non-accessible after final adjustmentof the operative size of said port to prevent unauthorized change of thesize after final calibration.

This invention relates to a carburetor.

It relates in particular to a charge forming device embodying within thefuel system, a metering rod for regulating the flow of fuel between thesource thereof and the carburetor mixing conduit. Following normalcarburetor construction in which a metering rod it utilized, the'rod isdisposed within an orifice formed in a passage communicating thecarburetor fuel bowl with the fuel nozzle. The metering rod isadjustable in response to the carburetor actuating mechanism for thepurpose of providing a more accurate and metered flow of fuel to themixture conduit. According to the' present invention, means is providedin the fuel passage communicating the fuel bowl with the fuel nozzle,for passing a second stream" of" fuel to form a by-pass around themetered stream, particularly under engine idle conditions.

The function of this by-pass opening is to provide a more accurate flowof fuel under particular carburetor operating conditions and tosupplement the flow passing through the main jet as defined by themetering rod. The by-pass opening is preferably provided with a valveelement for varying the fuel flow through said by-pass to provide a fineadjustment and consequently a more accurate control over the flow offuel passing through the nozzle.

The efficiency and desirability of metering rods in charge formingcarburetors, has long been known and proven to be most desirable. Themetering rod arrangement regardless of'how it is controlled whether fromthe carburetor orifice to define a variable opening for passage offueltherethrough.

' To meet the ever increasing and acute demands of industry, it has beennecessary to provide means for more accurately regulating the passage offuel that enters the carburetor mixing conduit. More particularly thereis an ever urgent need for regulating the combustible air fuel mixturefor the purpose of minimizing the amount of unburned hydrocarbons whichare passed to the atmosphere in the course of the operation of theengine. This creation of excessive hydrocarbon, commonly referred to asa smog condition, results in a large part from .an overly rich air fuelmixture being directed from the carburetor tothe engine. In view of thediverse accessories which the ordinary automobile engine is required tooperate, suchxas the air conditioning system, power steering, etc.,

United States Patent" it has become increasingly difficult to assure aconcise and proper fuel flow to the carburetor mixtrue conduit under allcircumstances.

Although the use of a metering rod does go a considerable distance inproviding fuel control, the metering rod is not the final solution tothe problem. For one thing, and as shown in FIGURE 1, in normaloperation, the metering rod is merely suspended within an orifice suchthat one portion of the metering rod end cooperates with the orifice todefinean annular opening. Since as a matter economics and conveniencethe metering rod is normally unguided except for the registration in theorifice, the annular opening provided thereby cannot be accuratelypredetermined.

Toward overcoming the above noted problem, of an in ability to provide asufficiently accurate fuel flow, the present metering rod orificebypassforms a supplementary flow of fuelwhich is substantially constantunder all conditions of carburetor operation. As an example, even whenthe metering rod is positioned such as to cut oif the flow of fuel fromthe fuel bowl to the nozzle, the bypass is so adjusted toafford thenecessary amount of fuel to sustain a desirable engine idle speed.

vA further circumstance prompting the development of the fuel bypassarrangement, arose from the desire for a multi use carburetorarrangement having a basically standard construction. In order to adaptto a number of different size engines however, it is necessary that thefuel flow characteristics of the carburetor be regulated in accordancewith the engine requirements. The present arrangement permits readyinterchange of parts particularly of fuel metering plate containing therespective primary and bypass fuel passages. Further, the presentlydisclosed arrangement provides a simple means for adjusting the fuelbypass either prior to assembly of the carburetor, or subsequent toassembly thereof. It is found that for the most accurate calibration ofany carburetor the latter is preferable adjusted to its final settingwhile under simulated conditions such as on a test stand in which fuelflow is regulated in accordance with the air flow passing therethrough.The resulting mixture is thereby immediately indicated thereby dictatingpossible further adjustment of the carburetor jets.

FIGURE 1 in the drawing is a vertical, partial cross section of acarburetor embodying the present invention, with portions broken away.

FIGURE 2. is a segmentary view in cross section of a portion of thedevice shown in FIGURE 1.

FIGURE 3 is a view similar to FIGURE 2.

FIGURES 4 and 5 are views similar to FIGURE 2 illustrating alternativeforms of the invention.

FIGURE 6 is a view of an end of one form of metering screw.

Referring to FIGURE 1 the carburetor, together with the presentlydisclosed fuel bypass means therein, is shown generally and as relatedto a single barrel unit. It should .be borne in mind however, that thenovel concept to be herein described more fully, is not so limited to asingle barrel carburetor but may be utilized as well in multibarrelunits. The carburetor shown is formed of a plurality of several membersincluding a central body 10 having a lower flanged opening to which isattached a circular neck portion 11 by a plurality of bolts 12. The neckportion includes a peripheral flange 13 having bolt holes therein forengaging the intake manifold of an internal combustion engine. A- gasket14 is compressed between the respective neck and body portions to forman air tight seal and avoid leakage of air into the air-fuel mixtureformed within the carburetor.

The upper side of body 10 is provided with a sealing gasket 16. A cover17 affixed ot the carburetor body by a plurality of bolts 19 forms thedevice into a unitary member.

The body may be formed of any suitable material adapted to theapplication, and includes a fuel bowl 21 extending substantially thevertical length thereof, defining a fuel holding reservoir 15. Cover 17is provided with a valve assembly in which a valve 22 is threadablyretained, having an inlet 33 opening into fuel chamber 23 and having astrainer 24 disposed therein for removing solids from the fuel streamwhich would otherwise tend to damage or lodge within the carburetorconstricted passages and ports. Valve 22 includes a movable needleelement 26 having a conical forward end which engages a peripheral seat27 thereby defining an annular fiow passage when the needle is displacedfrom the seat.

Under normal engine operation, fuel is drawn from the tank 28 andconducted through line 29 by a mechanically or electrically actuatedpump 31. Pressurized fuel is then discharged into line 32 and thence tothe fuel inlet 33 communicated through a strainer 24 with fuel chamber23. Fuel reservoir contains fioat 35 which is pivoted on arm 34 at apivot point 36 such as a shaft or similar member, carried on adownwardly depending portion of cover 17. Lowering of the float willpermit needle element 26 to be displaced from its corresponding seat bythe pressure of the fuel in fuel chamber 23. The fiow of fuel intoreservoir 15 will continue until such time as the fuel level will causethe float 35 to rise sufiiciently thereby positioning needle element 26into its seat and thus precluding further fuel flow.

Internally, the carburetor consists of a mixture conduit 37 having anair inlet 38 at the upper end thereof which may be connected to an airfilter or the like. The air inlet or air horn is further provided with achoke valve 39 carried on a choke valve shaft 41 which is pivotallydisposed in the air horn.

Mixture conduit 37 is provided with a plurality of coaxially disposedventuris 42, 43, and 44 respectively, suspended from a wall of themixture conduit.

The lower or neck portion of the carburetor is provided with a movablethrottle 46 mounted to a throttle shaft 47, one end of which protrudesfrom the carburetor to operably engage a suitable actuating mechanism.The carburetor includes a fuel nozzle 48 having an inlet disposed in themain nozzle passage 49 and having a constricted end opening into theupper venturi 42. An air bleed passage 51 includes a constricted portion52 for delivering a limited air stream to nozzle 48.

Referring to FIGURES 1 and 2, the carburetor main fuel system comprisesreservoir 15 which normally maintains a predetermined level of fuel. Anintermediate passage communicates the fuel reservoir 15 with a fuel sump53.

Sump 53 is formed at the lower end of an upright cavity 54 in thecarburetor body. Sump 53 and cavity 54 are disposed generallyconcentrically, the sump portion having a smaller diameter than thecavity thereby defining a peripheral shoulder 56. A gasket or othersealing member 57 is compressibly urged against shoulder 56 by anorifice plate 58 which is in turn urged against the gasket by a tubularretainer 59 slidably, although closely received within the cavity 54 andmaintained in place by cover 17 bearing against the upper end of saidretainer.

Orifice plate 58 is provided with a plurality of openings includingorifice 61 which may be shown in FIGURE 3, be provided with taperedinlet and outlet ports. A second orifice or opening 62 is spaced fromorifice 61 and defines a supplementary or by-pass passage for fuelnormally passing through the orifice 61.

Fuel passing from the sump 53 will normally traverse the orifice plateand enter the main nozzle passage 49 prior to discharge through nozzle48. As is known in the prior art, orifice 61 is provided with asuspended metering rod 63. The metering rod is formed at the lower end,with a plurality of decreasingly sized diameters which sequentially aredisposed within the orifice 61 to define variable openings for passageof fuel from sump 53 into main nozzle passage 49.

Metering rod 63, although not completely shown, extends through thecarburetor cover 17 and may be engaged by a linkage connected tothrottle shaft 47 or by other means to regulate the position of themetering rod within the orifice 61 thus providing optimum fuel fiowtherethrough in accordance with the engine operating conditions.

The supplementary, or calibrating orifice 62 is provided with, orcooperative with a valve member 66 to be hereinafter described ingreater detail, whereby a variable opening is formed in the by-pass tosupplement main fuel flow.

Tubular member 59 is provided with a second longitudinal chamber 67formed therein and terminating at the cover 17. Alternatively, thiselongated chamber 67 may extend through the cover plate 17 for providingaccess to the valve element 66 for adjusting the latter either by ascrew driver or other similar tool. A plug 68 wedged in chamber 67provides a closure to the latter for avoiding leakage of air into thecarburetor or discharge of fuel therefrom.

The carburetor idle fuel system comprises an elongated chamber 71containing an idle jet 72. Jet 72, is communicated by an idle passage'73 formed in cover 17, with an elongated connecting passage 74 whichopens into an idle chamber 76, the latter is communicated with mixingconduit 37 at a point above the throttle plate 46 when the latter is inclosed position. Passage 77 communicated with idle chamber 76 opens intoan adjustable idle jet port 78 which is communicated with mixtureconduit 37 at a point downstream of throttle 46. Idle adjusting screw 79is threadably carried in the idle port and is normally adjusted to giveoptimum fuel feed to the engine when the latter is at idle speed andthrottle 46 is in closed position.

Referring to FIGURE 3, the shown embodiment of the invention utilizes asvalve element 66 a threaded set screw or the like carried in the orifice62. The valve element 66 as shown is provided with an elongated slot 81extending longitudinally thereof, the slot having a cross section as todefine a uniformly decreasing cross sectional area as the slotprogresses toward one end of the valve element. Referring particularlyto FIGURE 6, the valve element is provided with a generally triangularshaped slot having the largest or widest portion thereof at the lowerend of the valve element and decreasing gradually toward the upper endto a virtually negligible opening. Thus by advancing or rotating thethreaded valve element 66 within the threaded orifice 62, it is possibleto vary proportionately the cross sectional opening of the fuel passagedefined by the triangular slot 81. For example, and referring to FIGURE3, as the valve element 66 is rotated to withdraw the same from theorifice plate. The fuel passage formed between slot 81 and the walls oforifice 62 will increase in size and allow a greater fuel flow throughthe orifice. Elongated chamber 67 is thus disposed preferably insubstantial alignment With valve element 66 in order that the adjustingtool may be inserted within the elongated chamber 67 with the plug 68removed. After needed adjustment, plug 68 is of course, inserted withinthe chamber 67 and sufficiently expanded or upset to form the necessaryfluid tight seal.

FIGURE 4 illustrates another alternative embodiment of the inventionwherein valve element 86 is shown cooperatively disposed with respect toa supplementary orifice 87 formed within orifice plate 88. In thisinstance, however, the valve element 86 is threadably retained withinthe carburetor body portion 89 and particularly within the accesspassage 91.

As shown in FIGURE 4, the lower end of access passage 91 is providedwith a constricted threaded portion which terminates at shoulder 92.Orifice 87 is disposed in vertical alignment with access passage 91 thatthe valve element 86 may correctly seat within the conical seat 93formed at the exit at orifice 87. The valve element 86 may therebyrotate as to advance or withdraw the valve element from position withthe seat 93 thereby defining the annular opening formed to regulate thesecondary flow of fuel which by-passes main orifice 94.

In a further embodiment of the invention, as shown in FIGURE 5, thebasic principal of bypassing the main orifice by means of asupplementary adjustable fuel flow regulator it is shown, wherein theadjustable valve element 97 is threadably retained in the lower portionof the fuel sump 98. In this embodiment of the invention it is, ofcourse, unnecessary to provide an access passage through the carburetorbody in alignment with the secondary or by-pass passage 99. Thus, thevalve member 97 may be readily adjusted from a point external to thecarburetor in such manner as to position the forward point 101 withinthe conically shaped seat 102 in the lower face of the orifice plate103. Valve member 97 is of course provided with a suitablecircumferential seal 104 to suitably define a fluid tight barrierparticularly since the adjusting means is at the lower side of thecarburetor and will be immersed in fuel at all times.

It is clear from the foregoing description of the invention as relatedto the carburetor herein described, that it is possible to obtain agreater degree of accuracy in carburetor calibration in the instance ofa use of metering rods incorporated into the carburetor structure. Amongthe advantages to be derived from the adjustable fuel bypass about themain metering rod orifice, is the feature of more accurate carburetorcalibration particularly to minimize the effects of unburnedhydrocarbons which result from accessively rich fuel particularly atengine idle. It is clear that in this latter mentioned condition it isunnecessary for the fuel metering rod 63 to be fabricated with a greatdegree of accuracy so as to form a precise annular passage with thecorresponding Orifice in the Orifice plate 58. To the contrary, it ispreferable that the metering rod 63 to permitted to descend sufficientlyinto the main orifice to seat and form tight annular seal. Thus theby-pass passage formed by valve member 66 will constitute the solesource of fuel supplied from the carburetor Sump 53 into the main nozzlepassage 49. Thus the fuel bypass adjustment might be utilized to obtaina desired carburetor flow test curve at any of several settings of themetering rod. For example, the bypass adjustment might be calibrated atengine idle, or at any other intermediate step of the metering rod. Theselecting of the exact point of by-pass adjustment is of coursepreferably at that section of the carburetor flow curve considered to bemost critical.

The use of the by-pass valve arrangement thereby not only simplifies thecarburetor structure but also permits a suitable adjustment to thecarburetor to insure uniformity of a particular type of unit inaccordance with the size of internal combustion engine to which it isassociated.

Further, it is understood that the problem of replacement of an entireorifice plate 58 is readily accomplished by merely removing theelongated retainer 59 so as to permit removal of the orifice plate andthe insertion of a different size plate should the engine require thelatter. It should be mentioned that both for the initial insertion ofthe orifice plate 58 and for subsequent replacement thereof, theadequate means may be provided Within the Well or at the peripheralshoulder 56 to properly align the orifice plate with the respectiveelongated chambers 54 and 67 positioned thereabove. To this end the flatorifice plate may be made irregularly shaped such as in the form of atriangle, hexagon or other geometric shape which would permit insertionwithin the carburetor wall only in the proper position.

It is clear from the foregoing description that the carburetor utilizingthe herein described bypass fuel passage possesses many advantagesheretofore lacking in similar carburetor construction. It is alsounderstood that certain modifications and changes may be made in thephysical structure of the described device Without departing from thespirit and substance of the invention as defined in the claims appendedhereto.

I claim:.

1. A charge forming device for an internal combustion engine including abody:

(1) A fuel reservoir formed in the body.

(2) a mixture conduit in said body having an air inlet,

(3) a throttle movably positioned in said mixture conduit for regulatingthe passage of air fuel mixture therethrough,

(4) a fuel system communicating said reservoir with said mixing conduitand including:

(A) a fuel nozzle having a discharge end opening into said mixtureconduit and having an inlet,

(B) means including a removable insert forming a fuel passagecommunicating said fuel nozzle inlet with said reservoir,

(C) an orifice disposed in said removable insert and an elongatedremovable retainer holding said insert in position,

(D) a suspended metering rod having a metering end disposed in saidorifice, said metering rod being reciprocably movable to define avariable annular opening in said orifice,

(E) adjustable bypass means including a secondary fuel portcommunicating said nozzle inlet with said fuel reservoir,

(F) alignment means for aligning said orifice with said metering rod,

(G) valve means for adjusting said adjustable bypass means,

(H) an access passage in alignment with said valve means, and

(I) obstructing means for said access passage to prevent further accessto said valve means after adjustment thereof.

References Cited UNITED STATES PATENTS 1,579,600 4/ I926 Durante 261-511,586,601 6/ 1926 Booty 261-50 2,084,607 6/ 1937 Bicknell 261--5l X2,186,480 1/1940 Ensign 261-51 X 2,341,694 2/1944 Coffey 261-51 X2,914,307 11/ 1959 Eickmann.

3,086,757 4/1963 Smith 26151 X 3,330,543 7/ 1967 Mennesson.

3,343,820 9/1967 Elliott 261-51 X HARRY B. THORNTON, Primary Examiner.

T. R. MILES, Assistant Examiner.

